I just published a new patch for OS X, below is a description of the patch. Check it out.
This is a patch for removing the default OS X behavior of always starting iTunes when the play button on the keyboard is pressed. This feature can be useful for a lot of users, but it can also be annoying if you are using VLC or other similar programs that support the media keys.
The Patch script will patch the Remote Control Daemon to prevent it from starting iTunes whenever you press the play button on the keyboard or an external remote control. This will only prevent iTunes from starting, all other functions (like play/pause while iTunes is running) will continue to work as before.
Lastly, this program will backup the original file in case if you would like to restore the original functionality.
For more information please visit the Play Button iTunes Patch page.